Horizontal-axis hydrokinetic water turbine system

ABSTRACT

A hydrokinetic water turbine system includes two turbine assemblies each having a frame structure, a horizontally-disposed shaft supported by the frame structure, and a rotor secured to the shaft. The rotor has a plurality of spaced-apart blades so that the flowing stream of water revolves the rotor. The blades are filled with a foam material to reduce weight and increase buoyancy. The frame structure is an open frame structure and includes frame members adapted to reduce a coefficient of drag of the frame structure. The frame members are filled with a foam material to reduce weight and increase buoyancy. The two turbine assemblies are secured side by side with shafts coaxial and the rotors rotating in opposite directions. The shafts can drive electric generators located out of the water or under the water. The underwater generators can be direct drive, low speed, high output generators.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation-in-part (CIP) application of U.S.patent application Ser. No. 13/191,537 filed on Jul. 27, 2011, thedisclosure of which is expressly incorporated herein in its entirety byreference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

Not Applicable

PARTIES TO A JOINT RESEARCH AGREEMENT

Not Applicable

REFERENCE TO APPENDIX

Not Applicable

FIELD OF THE INVENTION

The field of the present invention generally relates to apparatus thatconvert the movement of fluid into rotational mechanical motion for thegeneration of mechanical power or other useful purposes and, moreparticularly, to hydrokinetic water turbines that harness flowing watersuch as in rivers, streams, canals, industrial outflows, and the likefor the generation of mechanical power or other useful purposes.

BACKGROUND OF THE INVENTION

First attempts at harnessing water as a source of energy were throughwaterwheels used for grinding, pumping, and driving various types ofequipment. Some accounts suggest waterwheels were first used as long as4,000 years ago. These water wheels used either the elevation changeacross the wheel to turn it as in the case of an overshot waterwheel orused the velocity of the water to turn the wheel as in an undershot orvertically mounted waterwheel. The undershot and vertically mountedwaterwheels were based on the principle of reaction forces, with theforce of the water pushing buckets or paddles along causing the wheel toturn. Generally, this was a highly inefficient means of energyextraction.

In about 1931, the French inventor Georges Darrieus developed theconcept of a vertical-axis wind turbine using the principle of liftinstead of reaction forces. However, the principle is essentially thesame whether the turbine is used in wind or in water. In fact, theDarrieus-type wind turbines have been adapted to vertical-axishydrokinetic turbines. The most significant difference is that theDarrieus-type vertical-axis hydrokinetic turbines utilize straightblades as opposed to an eggbeater design of the original Darrieus windturbine. These Darrieus-type vertical-axis hydrokinetic turbines have aseries of aerodynamically shaped blades that are mounted parallel to avertical central shaft in a concentric arrangement. The individualhydrofoil-shaped blades are connected to the central shaft by supportarms. The shaft transmits torque to a generator or other power transferdevice. These hydrokinetic turbines can be supported by floatingplatforms anchored to the river bottom/sides or structures supported onthe river bottom.

While these prior water turbines have been shown to be a potentiallyviable technology, commercially available water turbine systems have notbeen cost effective because they are expensive to manufacture andassemble and because they produce relatively small amounts of power dueto their low efficiencies. Additionally, they are difficult to transportand install. Also, they are not particularly efficient in extractingenergy and can create a significant impediment to a waterways flow.Accordingly, there is a need in the industry for an improvedhydrokinetic water turbine system.

SUMMARY OF THE INVENTION

Disclosed are hydrokinetic water turbine systems that are an improvementover the existing hydrokinetic turbine systems described above.Disclosed is a hydrokinetic water turbine system configured to be placedin a flowing stream of water. The hydrokinetic water turbine systemcomprises, in combination, a frame structure, a shaft supported by theframe structure to rotate about a horizontally-disposed central axis ofthe shaft, a rotor secured to the shaft and having a plurality ofspaced-apart blades so that the flowing stream of water revolves therotor about the central axis of the shaft, and an underwater electricgenerator directly driven by the rotor.

Also disclosed is hydrokinetic water turbine system configured to beplaced in a flowing stream of water that comprises, in combination, aframe structure, a shaft supported by the frame structure to rotateabout a horizontally-disposed central axis of the shaft, and a rotorsecured to the shaft and having a plurality of spaced-apart blades sothat the flowing stream of water revolves the rotor about the centralaxis of the shaft. The rotor includes longitudinally spaced apartsupport discs fixed to the shaft and the blades extend between andthrough the support discs. The blades are fixed to the support discs byfasteners extending from edges of the support discs and perpendicular tolongitudinal axes of the blades.

Also disclosed is a hydrokinetic water turbine system configured to beplaced in a flowing stream of water. The water turbine system comprises,in combination, first and second hydrokinetic turbine assemblies. Thefirst hydrokinetic turbine assembly comprises a frame structure, a shaftsupported by the frame structure to rotate about a horizontally-disposedcentral axis of the shaft, a rotor secured to the shaft and having aplurality of spaced-apart blades so that the flowing stream of waterrevolves the rotor about the central axis of the shaft, and anunderwater electric generator directly driven by the rotor. The secondhydrokinetic turbine assembly comprises a frame structure, a shaftsupported by the frame structure to rotate about a horizontally-disposedcentral axis of the shaft, a rotor secured to the shaft and having aplurality of spaced-apart blades so that the flowing stream of waterrevolves the rotor about the central axis of the shaft, and anunderwater electric generator directly driven by the rotor. The firstand second hydrokinetic turbine assemblies are secured together suchthat the shafts the first and second hydrokinetic turbine assemblies arecoaxial and the flowing water rotates the rotors of the first and secondhydrokinetic turbine assemblies in opposite directions.

From the foregoing disclosure and the following more detaileddescription of various preferred embodiments it will be apparent tothose skilled in the art that the present invention provides asignificant advance in the technology and art of hydrokinetic waterturbine systems. Particularly significant in this regard is thepotential the invention affords for a system that is relatively easy totransport and install, relatively inexpensive to produce and assemble,and produces a relatively large amount of mechanical power and/orelectrical power for its size and weight. Additional features andadvantages of various embodiments of the invention will be betterunderstood in view of the detailed description provided below.

BRIEF DESCRIPTION OF THE DRAWINGS

These and further features of the present invention will be apparentwith reference to the following description and drawing, wherein:

FIG. 1 is a perspective view of a horizontal-axis hydrokinetic waterturbine system according to a first embodiment of the present invention;

FIG. 2 is a water turbine assembly of the hydrokinetic water turbinesystem of FIG. 1;

FIG. 3 is a front elevational view of the water turbine assembly of FIG.1;

FIG. 4 is a left side elevational view of the water turbine assembly ofFIGS. 2 and 3;

FIG. 5 is a top plan view of the water turbine assembly of FIGS. 2 to 4;

FIG. 6 is a sectional view taken along line 6-6 of FIG. 5;

FIGS. 7 A and 7B are sectional views taken along line 7-7 of FIG. 3,showing rotors of the two water turbine assemblies adapted for rotationin opposite directions;

FIG. 8 is a sectional view taken along line 8-8 of FIG. 3;

FIG. 9 is enlarged fragmented view taken from line 9 of FIG. 6;

FIG. 10 is enlarged fragmented view taken from line 10 of FIG. 6;

FIG. 11 is diagrammatic view of a hydrofoil illustrating geometricfeatures;

FIG. 12 is an enlarged cross-sectional view of a hollow, foam-filledhydrofoil-shaped frame member of the water turbine assembly of FIGS. 2to 4;

FIG. 13 is an enlarged fragmented cross-sectional view of a hollow,foam-filled frame member of the water turbine assembly of FIGS. 2 to 4;

FIG. 14 is another cross-sectional view of the hollow, foam-filledcircular-shaped frame member of FIG. 13;

FIG. 15 is a perspective view of a horizontal-axis hydrokinetic waterturbine system according to a second embodiment of the presentinvention;

FIG. 16 is a perspective view of one of the pontoon assemblies of thehydrokinetic water turbine system of FIG. 15, wherein the associatedwater turbine assembly is in a raised position out of the water;

FIG. 17 is a perspective view of the pontoon assembly of FIG. 16,wherein the water turbine assembly is in a lowered position so that itis below water;

FIG. 18 is a left side elevational view of the pontoon assembly of FIG.17;

FIG. 19 is a front elevational view of the pontoon assembly of FIGS. 17and 18;

FIG. 20 is a top plan view of the pontoon assembly of FIGS. 17 to 19;

FIG. 21 is a left side elevational view of the water turbine assembly ofthe pontoon assembly of FIGS. 17 to 19;

FIG. 22 is a front elevational view of the water turbine assembly ofFIG. 21;

FIG. 23 is a top plan view of the water turbine assembly of FIGS. 21 and22;

FIG. 24 is a front elevational view of a direct-drive power generationassembly of the water turbine assembly of FIGS. 21 to 23;

FIG. 25 is a top plan view of the power generation assembly of FIG. 24;

FIG. 26 is a left side elevational view of the power generation assemblyof FIGS. 24 and 25;

FIG. 27 is a schematic front view of the power generation assembly ofFIGS. 24 to 26 showing a pressure compensation system;

FIG. 28 is a block diagram of the pressure compensation system of FIG.27;

FIG. 29 is an enlarged fragmented perspective view a connection betweena blade and a support disc of a rotor of the water turbine assembly ofFIGS. 21 to 23; and

FIG. 30 is an end view the connection of FIG. 29.

It should be understood that the appended drawings are not necessarilyto scale, presenting a somewhat simplified representation of variouspreferred features illustrative of the basic principles of theinvention. The specific design features of the hydrokinetic waterturbine systems as disclosed herein, including, for example, specificdimensions and shapes of the various components will be determined inpart by the particular intended application and use environment. Certainfeatures of the illustrated embodiments have been enlarged or distortedrelative to others to facilitate visualization and clear understanding.In particular, thin features may be thickened, for example, for clarityor illustration. All references to direction and position, unlessotherwise indicated, refer to the orientation of the hydrokinetic waterturbine systems illustrated in the drawings. In general, up or upwardrefers to an upward direction within the plane of the paper in FIGS. 4and 8 and down or downward refers to a downward direction within theplane of the paper in FIGS. 4 and 8. Also in general, front or forwardrefers to a direction facing the flow of water or upstream, that is adirection toward the left within the plane of the paper in FIGS. 4 and 8and rear or rearward refers to a direction facing away from the flow ofwater or downstream, that is a direction toward the right within theplane of the paper in FIGS. 4 and 8.

DETAILED DESCRIPTION OF CERTAIN PREFERRED EMBODIMENTS

It will be apparent to those skilled in the art, that is, to those whohave knowledge or experience in this area of technology, that many usesand design variations are possible for the improved hydrokinetic waterturbine systems disclosed herein. The following detailed discussion ofvarious alternative embodiments will illustrate the general principlesof the invention. Other embodiments suitable for other applications willbe apparent to those skilled in the art given the benefit of thisdisclosure.

FIG. 1 illustrates a horizontal-axis hydrokinetic water turbine system10 configured to be placed in a flowing stream of water according to afirst embodiment of the present invention. The illustrated hydrokineticwater turbine system 10 includes two water turbine assemblies 12 eachhaving a horizontal axis water wheel or rotor 14 but it is noted thatthe hydrokinetic water turbine system 10 can alternatively have anyother quantity of water turbine assemblies 12. The illustrated first andsecond water turbine assemblies 12 are rigidly bound or secured togetherside-by-side so that the first and second rotors 14 are coaxial andextend laterally across the flow or stream of water (indicated by arrow16), that is, substantially perpendicular to the flow of water 16. Thefirst and second water turbine assemblies 12 are substantially the sameexcept that their rotors 14 rotate in opposite directions as describedin more detail below. The counter rotating rotors 14 result in addedstability of the hydrokinetic water turbine system 10 and reduces forcesand torque on associated mooring/support systems.

As shown in FIGS. 2 to 10, each illustrated water turbine assembly 12includes a frame structure 18, a rotating horizontal-axis central shaft20 connected to the frame structure 18 through bearings 22, a rotor 14which revolves about the central axis 24 of the shaft 20 and includestwo sets of four equally-spaced blades 26, 28 connected to end orsupport discs 30 that are bolted to the central shaft 20. The two setsof blades 26, 28 are staggered in configuration to improve efficiency asdescribed in more detail below.

The illustrated frame structure 18 is a substantially rectangular andopen frame structure having several vertical and horizontal framemembers 32, 34 secured together to form the box-like frame structure 18.The illustrated frame structure 18 is sized and shaped to support therotor 14 entirely below the surface of the water. The frame members 32,34 are secured together in any suitable manner such as, for example,mechanical fasteners, welding, and/or the like. The illustrated framestructure 18 has a pair of laterally spaced apart end assemblies whicheach include front and rear vertical frame members 32A, 32B, top andbottom horizontal frame members 34A, 34B that connect the tops andbottoms of the front and rear vertical frame members 32A, 32B, and apair of vertically spaced-apart central horizontal frame members 34C,34D that are secured to outer sides of the front and rear verticalmembers 32A, 32B between the top and bottom horizontal members 34A, 34B.The illustrated end assemblies also include a pair of shaft supportvertical frame members 32C, 32D extending between the top and bottomhorizontal frame members 34A, 34B and located between the front and backvertical frame members 32A, 32B to support a bearing plate assembly 36as described in more detail below. Top and bottom front horizontal framemembers 34E, 34F extend between the front vertical frame members 32A ofthe end assemblies and top and bottom rear horizontal frame members 34G,34H extend between the rear vertical frame members 32B of the endassemblies. Front and rear central vertical frame members 32E, 32Fextend between the top and bottom front horizontal frame members 34E,34F and the top and bottom rear horizontal frame members 34G, 34Hrespectively at central locations between the end assemblies. Top andbottom central horizontal frame members 34I, 34J are secured at the topand bottoms of the front and back central vertical frame members 32E,32F. It is noted that the frame structure 18 can alternatively have anyother suitable configuration.

The illustrated individual frame members 32, 34 are each designed toreduce the coefficient of drag of the frame structure 18. Theillustrated frame members 32, 34 that extend in a directionperpendicular to the flow of water 16 are shaped as hydrofoils in crosssection to reduce a coefficient of drag of the frame structure 18 (bestshown in FIG. 12). The illustrated frame members 32, 34 that extend in adirection parallel to the flow of water 16 have substantiallybullet-shaped ends to reduce the coefficient of drag of the framestructure 18 (best shown in FIGS. 13 and 14). It is noted that all oronly a portion of the frame members 32, 34 can be shaped in this mannerand that any other suitable shapes can alternatively be utilized but mayhave less or no benefit of the reduced coefficient of drag of the framestructure.

FIG. 11 illustrates the cross section of an airfoil or hydrofoil whichcan be shaped to cause a desired aerodynamic effect when fluid flowsthere over in a direction from a leading edge to a trailing edge. A meancamber line of a hydrofoil is the locus of points halfway between thespaced-apart upper and lower surfaces as measured perpendicular to themean camber line itself. The most forward and rearward points of themean camber line are the leading and trailing edges, respectively. Astraight line connecting the leading and trailing edges is a chord lineof the hydrofoil, and a distance from the leading to the trailing edgemeasured along the chord line is simply designated the chord (c) of theairfoil. A thickness of the airfoil is the distance from the upper tothe lower surface, measured perpendicular to the chord line, and varieswith distance along the chord. The maximum thickness, and where itoccurs along the chord, is an important design feature of the airfoil.Camber is the maximum distance between the mean camber line and thechord line, measured perpendicular to the chord line. Both the maximumthickness and the camber are usually expressed in terms of a percentageof the chord length; for example, a 12% thick airfoil has a maximumthickness equal to 0.12 c.

The National Advisory Committee for Aeronautics (NACA) has developedstandardized airfoil or hydrofoil profiles and utilizes a four digitidentification system. The NACA four-digit identifications define aprofile by: (1) a first digit describing maximum camber as percentage ofthe chord; (2) a second digit describing the distance of maximum camberfrom the airfoil leading edge in tens of percents of the chord; andthird and fourth digits describing maximum thickness of the airfoil aspercent of the chord. For example, FIG. 11 shows a NACA 2412 airfoilhaving a maximum camber of 2% located 40% (0.4 chords) from the leadingedge with a maximum thickness of 12% of the chord. Four-digit seriesairfoils by default have maximum thickness at 30% of the chord (0.3chords) from the leading edge. FIG. 12 shows a NACA 0015 airfoil whichis symmetrical, the 00 in the identification indicates that the airfoilhas no camber. The 15 in the identification indicates that the airfoilhas a 15% thickness to chord length ratio: the airfoil is 15% as thickas it is long.

The flow of water over the hydrofoil can result in an aerodynamic force(per unit span) on the hydrofoil. The relative water stream is themagnitude and direction of the free-stream velocity far ahead of thehydrofoil. The angle between the chord line and relative water stream isdefined as the angle of attack of the hydrofoil. By definition, thecomponent of the aerodynamic force perpendicular to the relative waterstream is the lift and the component of the force parallel to therelative water stream is the drag. The hydrofoil may be visualized asbeing supported by an axis perpendicular to the hydrofoil, and takenthrough any point on the hydrofoil. The hydrofoil has a tendency totwist about this axis; that is, there is an aerodynamic moment exertedon the hydrofoil. Lift is primarily a function of the shape of thehydrofoil and the angle of attack, the greater the camber and thegreater the angle of attack, the greater the lift. Thus the framemembers having a hydrofoil shape in cross section, can be shaped toprovide a desired effect.

As shown in FIG. 12, the illustrated frame members 32, 34 that extendperpendicular to the flow of water have a hydrofoil shape of NACA 0015to reduce a coefficient of drag of the frame structure 18. Thissymmetrical hydrofoil minimizes drag without substantially creating liftwhen positioned in the flow stream with a zero attack angle. It is notedthat the hydrofoil shape of these frame members 32, 34 can alternativelybe any other suitable shape depending on the aerodynamic effect desired.When these frame members 32, 34 have a profile that is the same as theblades 26, 28 as discussed in more detail below, the commonality of theprofile of the blades 26, 28 and the frame members 32, 34 allows foreasy mass production of a significant portion of the hydrokinetic waterturbine system 10.

As shown in FIGS. 13 and 14, the illustrated frame members 34 thatextend parallel to the flow of water 16 can be square in cross sectionand have substantially bullet-shaped ends to reduce a coefficient ofdrag of the frame structure 18. The illustrated frame members 34 ofFIGS. 2 to 4 comprise round tubes having bullet shaped end-caps 38attached to ends thereof. The end caps 38 can be secured to the tubes inany suitable manner. The end caps 38 can be formed of any suitablematerial such as, for example, can be molded of a plastic. It is notedthat these frame members 34 can alternatively have any other suitableshape depending on the aerodynamic effect desired and can be formed inany other desired manner such as an integral one-piece component.

Each of the illustrated frame members 32, 34 are hollow and comprisealuminum in order to reduce weight but it is noted that the framemembers 23, 34 can alternatively be solid and/or comprise any othersuitable material such as, for example, carbon fiber composite, but itmay result in a heavier and/or costlier structure 18. The illustratedframe members 23, 34 are hollow extrusions but it is noted that theframe members 32, 34 can alternatively be formed in any other suitablemanner but it may result in a heavier and/or costlier frame structure18. The illustrated hydrofoil-shaped hollow aluminum extrusions areprovided with internal bracing or ribs 40 to increase strength. Theillustrated hollow portions or cavities of the frame members 32, 34 arefilled with a foam material 42 to increase buoyancy of the framestructure 18. The foam material 42 can be any suitable material such as,for example, a foamed plastic material and the like. It is noted thatthe foamed material can be eliminated if desired in some or all of theframe members 32, 34 in applications where a lesser amount of or nobuoyancy is not desired.

The illustrated rotor shaft 20 is supported by the frame structure 18 sothat the shaft 20 rotates about the horizontally-disposed central axis24 of the shaft 20. The shaft 20 is oriented to extend laterally acrossthe frame structure 18 between the bearing plate assemblies 36 so thatthe rotor shaft 20 is perpendicular to the flow of water 16. Theillustrated rotor shaft 20 is supported by a pair graphite sleevebearings 22 adapted for marine use. The illustrated sleeve bearings 22are held by the bearing plate assemblies 36 that located at the lateralends of the frame structure 18 to support the ends of the rotor shaft20. The sleeve bearings 22 are preferably water lubricated. Theillustrated shaft 20 is a solid aluminum round bar but any othersuitable configuration and/or material can alternatively be utilized.

The illustrated rotor 14 has its first, second, and third support discs30 rigidly secured to the shaft 20 and longitudinally spaced-apart alongthe length of the shaft 20. The support discs 30 can be rigidly securedto the shaft 20 in any suitable manner such as, for example, mechanicalfasteners, welding, and the like. The first set of four spaced-apartblades 26 extends between the first and second support discs 30 and areequally and circumferentially spaced apart about the shaft 20. Thesecond set of spaced-apart blades 28 extends between the second andthird support discs 30 and are equally and circumferentially spacedapart about the shaft 20. The illustrated rotor 14 has four blades 26,28 located in each gap between the support discs 30 but any othersuitable quantity of blades 26, 28 and/or support discs 30 canalternatively be utilized. The first set of blades 26 and the second setof blades 28 are staggered so that each set has blades between eachother when viewed facing the water turbine assembly 12. The illustratedfirst set of blades 26 is spaced apart by 90 degrees from one anotherand the illustrated second set of blades 28 is spaced apart 90 degreesfrom one another but the second set of blades 28 are offset 45 degreesfrom the first set of blades 26 (best shown in FIGS. 7A and 7B). Thisoffset between the first and second sets of blades 26, 28 allows forsmooth rotation of the rotor 14 as there almost always a blade 26, 28 atthe right location for rotation of the rotor 14. The illustrated blades26, 28 are rigidly secured to the support discs 30 to prevent relativemovement therebetween. The blades 26, 28 can be secured to the supportdiscs 30 in any suitable manner such as, for example, by welding and thelike. It is noted that the rotor 14 can alternatively have any othersuitable configuration.

The illustrated rotor blades 26, 28 have a hydrofoil shape in crosssection. As shown in FIG. 12, the illustrated blades 26, 28 have ahydrofoil shape of NACA 0015. It is noted that the hydrofoil shape ofthe blades 26, 28 can alternatively be any other suitable shape and/ororientation depending on the aerodynamic effect desired. It is notedthat the angle of attack of the blades 26, 28 continuously changes asthe blades 26, 28 rotate about the central axis 24 of the shaft 20. Asbest seen in FIGS. 7A and 7B, the blades 26, 28 of the first and secondwater turbine assemblies 12 face in opposite directions so that therotors 14 rotate in opposite directions.

Each of the illustrated blades 26, 28 are hollow and comprise aluminumin order to reduce weight but it is noted that the blades 26, 28 canalternatively be solid and/or comprise any other suitable material suchas, for example, carbon fiber composite, but it will result in heavierblades 26, 28. The illustrated blades 26, 28 are hollow extrusions butit is noted that the blades 26, 28 can alternatively be formed in anyother suitable manner but it may result in a heavier and/or costlierstructure. The illustrated hollow aluminum extrusions are provided withinternal bracing or ribs 40 to increase strength. The illustrated hollowportions or cavities of the blades 26, 28 are filled with a foammaterial 42 to increase buoyancy of the blades 26, 28 to ease rotationof the rotor 14. The foam material 42 can be any suitable foam materialsuch as, for example, a foamed plastic material and the like. When theblades 26, 28 are extruded aluminum, internally braced, and foam filled,they provide reduced weight and increased buoyancy while maximizingstructural strength.

The illustrated frame structure 18 also includes a support platform 44for an electrical power generator assembly 46 to be driven by themechanical power generated by the rotor 14. The electrical powergeneration assembly 46 can be of any suitable type. It is noted that theelectrical power generation assembly 46 can alternatively be replacedwith any other suitable output device operable by the mechanical energygenerated by the rotor 14 such as, for example, a pump or the like. Theillustrated support platform 44 is located at a top of the framestructure 18 so that the electrical power generation assembly 46 mountedon the support platform 44 can be positioned above the surface of thewater. The illustrated support platform 44 is also contiguous with alateral end of the frame structure 18 so that a mechanical powertransfer assembly 48 can vertically extend from an end of the shaft 20to an end of the support platform 44. The illustrated mechanical powertransfer assembly 48 comprises a chain and sprocket system having afirst sprocket 50 rigidly secured to an end of the rotor shaft 20, asecond sprocket 52 rigidly secured to a shaft of the electrical powergeneration assembly 46, and a chain 54 operably connecting the sprockets50, 52 so that rotation of the rotor shaft 20 rotates the electricalpower generation assembly 46 to produce electricity. It is noted thatthe mechanical power transfer assembly 48 can be of any other suitabletype but may increase cost and complexity of the water turbine assembly12.

In operation, the hydrokinetic water turbine assemblies 12 are rigidlybound or secured together side-by-side so that the first and secondrotors 14 are coaxial and extend laterally across the flow of water 16,that is, substantially perpendicular to the flow of water 16. The framestructure 18 is positioned within the water so that the rotors 14 arefully submerged but the electrical power generation assemblies 46 arelocated above the water level. As the flow of water passes through theopen frame structure 18 and the rotors 14, the rotors 14 are rotated inopposite directions by the flowing water. The mechanical power transferassembly 48 connected to the rotor shaft 20 drives the electrical powergeneration assembly 46 to produce electricity from the mechanical powergenerated by the flowing water.

FIG. 15 illustrates a horizontal-axis hydrokinetic water turbine system110 configured to be placed in a flowing stream of water 16 according toa second embodiment of the present invention. The illustratedhydrokinetic water turbine system 110 includes two pontoon assemblies112, each supporting a hydrokinetic water turbine assembly 114, that aremoored within a canal 116 by mooring lines 118. The illustrated pontoonassemblies 112 are bound or secured together side-by-side so that thewater turbine assemblies 114 are coaxial and extend laterally across theflow or stream of water 16, that is, substantially perpendicular to theflow of water 16. It is noted that additional pontoon assemblies 112 canbe added in a modular side-by-side manner if desired. The illustratedfirst and second water turbine assemblies 114 are substantially the sameexcept that their rotors rotate in opposite directions as described inmore detail above with regard to the first embodiment. The counterrotating rotors result in added stability of the hydrokinetic waterturbine system 110 and reduces forces and torque on the associatedmooring system.

FIGS. 16 to 20 illustrate the pontoon assembly 112 of the illustratedhydrokinetic water turbine system 110. It is noted that only one of thepontoon assemblies 112 is described in detail because the illustratedpontoon assemblies 112 are identical except for the rotors that rotatein opposite directions. The illustrated pontoon assemblies 112 eachinclude a pair of laterally spaced-apart pontoons 122, a supportstructure 124 connecting the pontoons 122, the water turbine assembly114, a hoist structure 126 for supporting a hoist 128 for raising thewater turbine assembly 114 out of the water (best shown in FIG. 16) andlowering the water turbine assembly 114 into the water (best shown inFIG. 17). The pontoons 122 can be of any suitable type for floating onthe surface of the water and supporting the remaining components of thepontoon assembly 112. The illustrated support structure 124 includessupports 130 that connect the pontoons 122 together at a distance suchthat the water turbine assembly 114 can be raised and lowered betweenthe pontoons 122. Decking or planking 132 is provided on the supports130 encircling an opening for raising and lowering the water turbineassembly 114 and hand rails 134 are provided about the decking 132. Theillustrated hoist structure 126 extends upward from the supports 130about the opening and supports a hoist beam 136 above the opening. Theillustrated hoist 128 includes a hoist rope 138 extending to the waterturbine assembly 114 via a pulley 140 located on the hoist beam 136 toraise and lower the water turbine assembly 114 between a raise positionwherein it is out of the water (best shown in FIG. 16) and a loweredposition wherein it is under the water (best shown in FIG. 17). Thehoist 128 can be of any suitable type and can be alternativelyconfigured in any other suitable manner.

As best shown in FIGS. 21 to 23, each illustrated water turbine assembly114 includes a frame structure 142, a direct drive electrical powergenerator assembly 144, and a first and second coaxial rotors 146, 148located on opposed lateral sides of the power generator assembly 144 andeach having a rotating horizontal-axis central shaft 150. Theillustrated shafts 150 each have an outer end connected to the framestructure 142 through a bearing assembly 152 and an inner end directlyconnected to a shaft 154 of the power generator assembly 144. Each ofthe rotors 146, 148 revolve about a horizontal, laterally extendingcentral axis 156 of the shaft 150 and includes a set of fourequally-spaced blades 158 connected to end or support discs 160 that arebolted to the central shaft 150. The blades 158 of the two rotors 146,148 are staggered in configuration to improve efficiency as describedabove with regard to the first embodiment of the invention.

The illustrated frame structure 142 is a substantially rectangular andopen frame structure having several vertical and horizontal framemembers 162, 164 secured together about the power generator assembly 144to form the box-like frame structure. The illustrated frame structure142 is sized and shaped to support the power generator assembly 144 andthe rotors 146, 148 entirely below the surface of the water. The framemembers 162, 164 are secured together in any suitable manner such as,for example, mechanical fasteners, welding, and/or the like. Theillustrated frame structure 142 includes rectangular-shaped boxstructures box structure 166, 168 secured to the top and the bottom of aframe 170 of the power generator assembly 144. The frame 170 of thepower generator assembly 144 is provided with at least one attachmentmember 172 such as, for example, an eye to which the hoist rope 138 isattached to raise and lower the frame structure 142 with the hoist 128.Front and rear bottom horizontal frame members 164A, 164B laterallyextend through and are secured to the bottom box structure 168. Frontand rear intermediate horizontal frame members 164C, 164D extend throughand are secured to the top box structure 166. Front and rear tophorizontal frame members 164E, 164F are spaced above the intermediatehorizontal frame members 164C, 164D to form the top of the framestructure 142. Left and right front vertical members 162A, 162Bvertically connect ends of the front top, intermediate and bottomhorizontal frame members 164A, 164C, 164E and left and right rearvertical members 162C, 162D vertically connect ends of the rear top,intermediate and bottom horizontal frame members 164B, 164D, 164F.Vertically spaced-apart horizontal frame members 164G, 164H, 164I, 164J,164K, 164L extend in the forward-rearward direction and are secured tothe vertical members 162A, 162B, 162C, 162D at the bottom, intermediateand top horizontal members 164A, 164B, 164C, 164D, 164E, 164F. Betweenthe bottom and intermediate horizontal members 164G, 164H, 164I, 164Jare a pair of vertically spaced apart horizontal support members 164M,164N, 164O, 164P extending in the forward and rearward direction andsecured to the front and rear vertical members 162A, 162B, 162C, 162D onboth the left and right sides of the frame structure 142. Extendingbetween the horizontal support members 164M, 164N, 164O, 164P are thebearing assemblies 152. Inclined cross members 174A, 174B extend fromthe tops of the vertical members 162A, 162B, 162C, 162D to the top boxstructure 166. It is noted that the frame structure 142 canalternatively have any other suitable configuration.

The illustrated individual frame members 162, 164, 174 are each designedto reduce the coefficient of drag of the frame structure 142 asdescribed above with regard to the first embodiment. It is noted thatall or only a portion of the frame members 162, 164, 174 can be shapedin this manner and that any other suitable shapes can alternatively beutilized but may have less or no benefit of the reduced coefficient ofdrag of the frame structure 142. Each of the illustrated frame members162, 164, 174 are hollow aluminum extrusions in order to reduce weightas described above with regard to the first embodiment but it is notedthat the frame members 162, 164, 174 can alternatively be solid and/orcomprise any other suitable material such as, for example, carbon fibercomposite, but it may result in a heavier and/or costlier structure. Theillustrated hollow portions or cavities of the frame members 162, 164,174 are filled with a foam material to increase buoyancy of the framestructure as described above with regard to the first embodiment. It isnoted that the foamed material can be eliminated if desired in some orall of the frame members 162, 164, 174 in applications where a lesseramount of or no buoyancy is not desired.

As best shown in FIGS. 24 to 28, the electrical power generator assembly144 includes an underwater, direct drive, low speed high output,electrical generator 176 that converts the mechanical energy of theturning rotors 146, 148 into electrical energy and can be of anysuitable type of electrical generator such as, for example, a radial gapgenerator or an axial gap generator. The illustrated generator 176 isconfigured as a direct drive generator. That is, the direct drivegenerator 176 includes no gear box, gears or the like to step up therotational speed of the generator shaft 154. Thus, the direct drivegenerator 176 rotates at the same rate as the rotors 146, 148 and isrelatively large to generate enough electricity from the motion of therotors 146, 148. The illustrated generator 176 operates at a low speedbetween about 60 RPM and about 80 RPM and preferably a speed of about 70RPM and has a high output of 35 kW or more.

The illustrated generator assembly 144 is also configured to operatewhile submerged entirely below the surface of the water. The illustratedgenerator assembly 144 has a sealed and pressurized housing 178 for thegenerator 176. Seals 180 are provided for the generator shaft 154 whichlaterally extends out of both sides of the housing 178. The interior ofthe housing 178 is pressurized and a pressure compensation system 182 isincluded to maintain the pressure within the housing 178 higher than thewater pressure surrounding the housing 178. As water pressure increasesaround the housing 178, a diaphragm switch or valve 184 of the pressurecompensation system 182 automatically allows pressured fluid (such as,for example, compressed air) to enter into the interior of the housing178 to maintain the interior pressure above the surrounding waterpressure. The pressurized fluid can be provided in any suitable mannersuch as, for example, a pressurized tank located within the housing, apressurized tank located outside the housing either below or above thesurface of the water and operably connected to the housing, a pump orcompressor located above the surface of the water and operably connectedto the housing, or a pump or compressor located below the surface of thewater and operably provided with a source of fluid to be compressed. Thehigher pressure within the housing 178 prevents water leakage into thehousing 178 even as the shaft seals 180 begin to wear. The illustratedgenerator 176 is naturally cooled by the surrounding water but an activecooling system can be included if desired.

Each illustrated water turbine assembly 114 has left and right rotors146, 148 that are identical except that the blades 158 are staggered inconfiguration to improve efficiency as described above with regard tothe first embodiment of the invention. Therefore only one of the rotors146, 148 will be described in detail. The illustrated rotor shaft 150 issupported between the power generation assembly shaft 154 and thebearing assembly 152 of the frame structure 142 so that the shaft 150rotates about the horizontally-disposed central axis 156 of the shaft150. The shaft 150 is oriented to extend laterally between the framestructure bearing assembly 152 and the power generator assembly shaft154 so that the rotor shaft 150 is perpendicular to the flow of water16. The inner end of the shaft 150 is provided with a hub 186 that issecured to a hub 188 of the power generation assembly shaft 154 torotatably support the inner end of the shaft 150. The illustratedbearing assembly 152 includes a graphite sleeve bearing adapted formarine use that rotatably supports the outer end of the shaft 150. Thesleeve bearing is preferably water lubricated. The illustrated shaft 150is a solid aluminum round bar but any other suitable configurationand/or material can alternatively be utilized.

The illustrated rotor 146, 148 has first and second support discs 160A,160B rigidly secured to the shaft 150 and longitudinally spaced-apartalong the length of the shaft 150. The illustrated support discs 160A,160B are rigidly secured to the shaft 150 with hubs 190 but can berigidly secured to the shaft 150 in any suitable manner such as, forexample, mechanical fasteners, welding, and the like. The illustratedset of four spaced-apart blades 158 extend between and through the firstand second support discs 160A, 160B and are equally andcircumferentially spaced apart about the shaft 150. The illustratedrotor 146, 148 has four blades 158 between the two support discs 160A,160B but any other suitable quantity of blades 158 and/or support discs160A, 160B can alternatively be utilized. The illustrated blades 158 arespaced apart by 90 degrees from one another. As best shown in FIGS. 29and 30, the illustrated blades 158 extend through openings 192 in thesupport discs 160A, 160B and are rigidly secured to the support discs160A, 160B by fasteners 194 in the form of pins to prevent relativemovement therebetween. The illustrated pins 194 extend from the edge 196of the support disc 160A, 160B and are substantially perpendicular tothe longitudinal axis 198 of the blades 158. Securing the blades 158 tothe support discs 160A, 160B in this manner reduces stress on theconnections and increases power due to the increased blade areaextending beyond the support discs 160A, 160B. It is noted that theblades 158 can alternatively be secured to the support discs in anyother suitable manner. It is noted that the rotor 146, 148 canalternatively have any other suitable configuration.

The illustrated rotor blades 158 have a hydrofoil shape in cross sectionas described above with regard to the first embodiment. Each of theillustrated rotor blades 158 are hollow and comprise aluminum extrusionsin order to reduce weight but it is noted that the blades 158 canalternatively be solid and/or comprise any other suitable material suchas, for example, carbon fiber composite, but it will result in heavierblades. The illustrated hollow portions or cavities of the blades 158are filled with a foam material to increase buoyancy of the blades 158to ease rotation of the rotor 146, 148 as described above with regard tothe first embodiment.

In operation, the pontoon assemblies 112 are rigidly bound or securedtogether side-by-side so that the rotors 146, 148 of the two waterturbine assemblies 114 are coaxial and extend laterally across the flowof water 16, that is, substantially perpendicular to the flow of water16. The water turbine assemblies 114 are lowered into the water with thehoist 128 so that the rotors 146, 148 and the power generator assemblies144 are each fully submerged. As the flow of water passes through theopen frame structures 142 and the rotors 146, 148, the rotors 146, 148of the two water turbine assemblies 114 are rotated in oppositedirections by the flowing water. The rotors 146, 148 directly drive theelectrical power generator assemblies 144 to produce electricity fromthe mechanical power generated by the flowing water.

Any of the features or attributes of the above described embodiments andvariations can be used in combination with any of the other features andattributes of the above described embodiments and variations as desired.

From the foregoing disclosure it will be apparent that the presentinvention provides an improved hydrokinetic water turbine system becausethe counter rotating rotors reduce torque on the system and thussimplified mooring and flotation devices can be used. Additionally, byutilizing a horizontal rotational axis, sleeve bearings can be utilizedand simple drive train mechanisms or a direct drive configuration can beused. Furthermore, by reducing the weight and increasing the buoyancy ofthe blades, lower flow velocity is required to rotate the rotor.Furthermore, by decreasing the drag of the frame structure within theflow stream, less forces are generated on the structure so that it canbe made lighter and can lower negative impacts on the stream and thusthe environment. The ability to have components of a relatively lightweight reduces costs, increases efficiency, enables the system to bemore easily transported and assembled, and allows the rotors to berotated with less force so that the system produces a relatively largevolume of electricity for its size and weight. It is believed that eachrotor and frame assembly will weigh about 3000 pounds and produce about20 kW of mechanical power at 2 m/s so that the full illustratedhydrokinetic water turbine system with two water turbine assemblies willweigh about 6000 pounds and produces about 40 kW at 2 m/s.

From the foregoing disclosure and detailed description of certainpreferred embodiments, it will be apparent that various modifications,additions and other alternative embodiments are possible withoutdeparting from the true scope and spirit of the present invention. Theembodiments discussed were chosen and described to provide the bestillustration of the principles of the present invention and itspractical application to thereby enable one of ordinary skill in the artto utilize the invention in various embodiments and with variousmodifications as are suited to the particular use contemplated. All suchmodifications and variations are within the scope of the presentinvention as determined by the appended claims when interpreted inaccordance with the benefit to which they are fairly, legally, andequitably entitled.

1. A hydrokinetic water turbine system configured to be placed in aflowing stream of water, said water turbine system comprising, incombination: a frame structure; a shaft supported by the frame structureto rotate about a horizontally-disposed central axis of the shaft; arotor secured to the shaft and having a plurality of spaced-apart bladesso that the flowing stream of water revolves the rotor about the centralaxis of the shaft; and an underwater electric generator directly drivenby the rotor.
 2. The hydrokinetic water turbine system according toclaim 1, wherein the electric generator is a low speed, high outputelectric generator.
 3. The hydrokinetic water turbine system accordingto claim 1, wherein the electric generator has a sealed and pressurizedhousing.
 4. The hydrokinetic water turbine system according to claim 3,wherein a pressure compensator maintains pressure in the housing higherthan a pressure of water surrounding the housing.
 5. The hydrokineticwater turbine system according to claim 1, wherein the blades are hollowand filled with a foam material to reduce weight and increase buoyancy.6. The hydrokinetic water turbine system according to claim 5, whereinthe blades are hydrofoils.
 7. The hydrokinetic water turbine systemaccording to claim 6, wherein the blades are adapted to generate lift torotate the rotor as the flowing stream of water passes the rotor.
 8. Thehydrokinetic water turbine system according to claim 1, wherein theframe structure comprises a substantially rectangular open structure. 9.The hydrokinetic water turbine system according to claim 8, wherein theframe structure comprises a plurality of frame members and the framemembers are hollow and filled with a foam material to reduce weight andincrease buoyancy.
 10. The hydrokinetic water turbine system accordingto claim 9, wherein the frame members are hydrofoils to reduce thecoefficient of drag of the frame structure.
 11. A hydrokinetic waterturbine system configured to be placed in a flowing stream of water,said water turbine system comprising, in combination: a frame structure;a shaft supported by the frame structure to rotate about ahorizontally-disposed central axis of the shaft; a rotor secured to theshaft and having a plurality of spaced-apart blades so that the flowingstream of water revolves the rotor about the central axis of the shaft;wherein the rotor includes longitudinally spaced apart support discsfixed to the shaft and the blades extend between and through the supportdiscs; and wherein the blades are fixed to the support discs byfasteners extending from edges of the support discs and perpendicular tolongitudinal axes of the blades.
 12. The hydrokinetic water turbinesystem according to claim 11, wherein the fasteners are pins.
 13. Thehydrokinetic water turbine system according to claim 11, wherein theplurality of spaced-apart blades comprises at least four blades.
 14. Thehydrokinetic water turbine system according to claim 11, furthercomprising a low speed, high output, underwater electric generatordirectly driven by the rotor.
 15. The hydrokinetic water turbine systemaccording to claim 11, wherein the blades are hollow and filled with afoam material to reduce weight and increase buoyancy.
 16. Thehydrokinetic water turbine system according to claim 15, wherein theblades are hydrofoils.
 17. The hydrokinetic water turbine systemaccording to claim 16, wherein the blades are adapted to generate liftto rotate the rotor as the flowing stream of water passes the rotor. 18.The hydrokinetic water turbine system according to claim 11, wherein theframe structure comprises a substantially rectangular open structure.19. The hydrokinetic water turbine system according to claim 18, whereinthe frame structure comprises a plurality of frame members and the framemembers are hollow and filled with a foam material to reduce weight andincrease buoyancy.
 20. The hydrokinetic water turbine system accordingto claim 19, wherein the frame members are hydrofoils to reduce thecoefficient of drag of the frame structure.
 21. A hydrokinetic waterturbine system configured to be placed in a flowing stream of water,said water turbine system comprising, in combination: a firsthydrokinetic turbine assembly comprising: a frame structure; a shaftsupported by the frame structure to rotate about a horizontally-disposedcentral axis of the shaft; a rotor secured to the shaft and having aplurality of spaced-apart blades so that the flowing stream of waterrevolves the rotor about the central axis of the shaft; and anunderwater electric generator directly driven by the rotor; a secondhydrokinetic turbine assembly comprising: a frame structure; a shaftsupported by the frame structure to rotate about a horizontally-disposedcentral axis of the shaft; a rotor secured to the shaft and having aplurality of spaced-apart blades so that the flowing stream of waterrevolves the rotor about the central axis of the shaft; and anunderwater electric generator directly driven by the rotor; and whereinthe first and second hydrokinetic turbine assemblies are securedtogether such that the shafts the first and second hydrokinetic turbineassemblies are coaxial and the flowing water rotates the rotors of thefirst and second hydrokinetic turbine assemblies in opposite directions.22. The hydrokinetic water turbine system according to claim 21, whereinthe underwater electric generator of each of the first and secondhydrokinetic turbine assemblies is a low speed, high output, underwaterelectric generator.
 23. The hydrokinetic water turbine system accordingto claim 22, wherein the rotor of each of the first and secondhydrokinetic turbine assemblies includes longitudinally spaced apartsupport discs fixed to the shaft and the blades extend between andthrough the support discs, and wherein the blades are fixed to thesupport discs by fasteners extending from edges of the support discs andperpendicular to longitudinal axes of the blades.
 24. The hydrokineticwater turbine system according to claim 21, further comprising a lowspeed, high output, underwater electric generator directly driven by therotor.
 25. The hydrokinetic water turbine system according to claim 21,wherein the blades are hollow and filled with a foam material to reduceweight and increase buoyancy.
 26. The hydrokinetic water turbine systemaccording to claim 25, wherein the blades are hydrofoils.
 27. Thehydrokinetic water turbine system according to claim 26, wherein theblades are adapted to generate lift to rotate the rotor as the flowingstream of water passes the rotor.
 28. The hydrokinetic water turbinesystem according to claim 21, wherein the frame structure comprises asubstantially rectangular open structure.
 29. The hydrokinetic waterturbine system according to claim 28, wherein the frame structurecomprises a plurality of frame members and the frame members are hollowand filled with a foam material to reduce weight and increase buoyancy.30. The hydrokinetic water turbine system according to claim 29, whereinthe frame members are hydrofoils to reduce the coefficient of drag ofthe frame structure.